The recent anthrax attack of 2001 underscored the reality of large-scale aerosol bioweapons attack by terrorist groups. It also revealed that there is an urgent and pressing need to discover and develop novel and potent antimicrobials that can be used therapeutically and prophylactically for biodefense against new bioattacks. The NIH and CDC have identified a number of High Priority pathogens based on their likelihood of causing widespread contagious disease and/or death to the general population. The long range goal of this Phase I SBIR is to discover and develop potent, broad-spectrum, and mechanistically-novel antimicrobials suitable for treating and/or preventing outbreaks of diseases like anthrax, plague, cholera, gastroenteritis, multidrug-resistant tuberculosis (MDR TB), and for tackling the growing problem of antibiotic resistant bacteria strains. This Phase I application aims to generate novel inhibitors of a bacterial enzyme-3-dehydroquinate dehydratase (DHQase) using molecular target- and structure-based approaches. DHQase is a key enzyme in the shikimate pathway that is essential for the biosynthesis of aromatic amino acids in microorganisms, plants and fungi. Specific aims of the application include: 1) cloning, expression and purification of recombinant DHQases from Bacillus anthracis, Yersinia pestis, Campylobacter jejuni, Vibrio cholera and Mycobacteria tuberculosis; 2) establishing DHQase inhibitor assays using the recombinant enzymes; 3) identifying small molecule chemical leads using experimental and computational screening methods; and 4) validating binding modes of inhibitor leads using X-ray crystallography of inhibitor/enzyme complexes. High resolution crystal structures of DHQase, with and without inhibitors, are available from preliminary studies, and crystallization conditions are well established in the laboratory of the PI. The commercial goal of this SBIR is the invention of one or more patentable molecular entities with broad cross-reactivity against DHQases and the pathogens from which they are derived. Enzyme inhibitors identified in the Phase I portion of this work will serve as leads for launching into a Phase II study, the goal of which will be to translate potent and selective inhibitors of High Priority pathogens into safe and effective clinical drug candidates for use as biodefense agents. [unreadable] [unreadable]